This invention relates generally to the field of telecommunications and more particularly to a method and system for protection switching in a telecommunications network.
Telecommunication networks often include protection switching architectures to maximize circuit availability. Protection schemes are dependent upon specific application requirements, as well as industry requirements. For Synchronous Optical-Network (SONET) fiber optic systems, for example, protection switching requirements include the ability to detect failures within 10 milliseconds and to complete a switch within 50 milliseconds after detection.
For Asynchronous Transfer Mode (ATM) networks, a typical means for protection switching includes an ATM virtual path ring. The ATM virtual path ring has a plurality of nodes that communicate with each other through two streams of traffic: a working traffic stream traveling around the virtual path ring in a first direction and a protect traffic stream traveling around the virtual path ring in the opposite direction for back-up. Each message is transmitted in both directions and thus received by a destination node from both the working and protect streams.
Each node in the ring generally includes two separate circuit packs to process the two traffic streams. The circuit packs determine which one of the circuit packs will process the traffic and thus determine whether traffic from the working or protect traffic stream will be used. In making this determination, the circuit packs communicate information back and forth. Messaging latency and/or limited bandwidth for communication between circuit packs may delay the determination. Because of this, there is a limit on the number of ATM traffic streams that can be concurrently supported while the protection switching requirements are maintained.
In accordance with the present invention, a method and system for protection switching in a telecommunications network are provided that substantially eliminate or reduce disadvantages and problems associated with previously developed systems and methods. In particular, each circuit pack has priority level data for the traffic stream, which allows the stream to be processed in order of priority in the event of a failure.
In one embodiment of the present invention, a method for protection switching in a telecommunications network is provided that includes receiving a plurality of primary and secondary sub-streams. Each primary sub-stream corresponds to a redundant secondary sub-stream. Each sub-stream has an associated priority level. Protection switching is provided for the sub-streams based on the priority levels.
Technical advantages of the present invention include providing an improved method for protection switching in a telecommunications network. In particular, each circuit pack for a routing terminal has a database for storing priority level data for the traffic stream. As a result, the traffic stream may be segmented based on priority in the event of a failure. Accordingly, the higher priority traffic, such as voice traffic, may be processed first in order to meet time requirements for switching, while the lower priority traffic with less strict time requirements, such as non-real time traffic, is processed after the high priority traffic.
Another technical advantage of the present invention includes providing a high capacity telecommunications node and ring with compliant protection switching for voice traffic. In particular, voice and other time sensitive and high priority traffic is identified and processed first in response to a failure in order to meet switching requirements. Lower priority traffic is processed after the higher priority traffic. As a result, the number of ATM or other suitable flows concurrently supported may be increased as a result of the prioritization because data traffic is not interfering with the requirements for voice protection switching times.
Other technical advantages will be readily apparent to one skilled in the art from the following figures, description, and claims.